Nice.
What about Ulpia Severina ?
I'm honestly not sure how to handle her. The evidence does seem to bear out that she may have ruled in her own right during the interregnum, but the interregnum was also almost certainly much shorter than the Historia Augusta would have us believe. Since she seems to disappear from the record after Tacitus's ascension, I'm assuming her power and influence more or less ended there, though I wouldn't be surprised if Tacitus' sought her assistance and she had a role in getting him to the purple IOTL.
For the sake of the Timeline though, assume she remains present in Tacitus's court, but any influence she exerts is likely to be behind the scenes. I'll try and work her in, but writing from the perspective of your standard popular historian, she's likely just as unknown in this world as she is in ours, so (as with a lot of important women of the era) is less likely to be mentioned more than in passing.